Telephone party line working



June 17, 1941. L Y 2,246,119

TELEPHONE PARTY LINE WORKING I Filed Aug. 29, 1940 FIG.

IN VENTOR Patented June 17, 1941 UNITED STATES- PATENT OFFICE TELEPHONE PARTY tins WORKING RobertHQBadgley, lldorrisPlains, N. .L, assignor to Bell Telephone Laboratories, Incorporated,

New York, N Y;, acorporation-of NewYrk Application August 29, 19.40, Serial No. 354,633 cla ms. (c1. 179 s7) This invention relates to signaling systems and particularly to multiparty line telephonesystems.

The object of this invention is :to provide economical and reliable means for selective party line ing and for selective pairty li jge'substa tion identification. t 1

- In accordance with one feature of this invention a highly selective relay deviceis placed at 'eachsubstation on a party line for the purpose of bringing the call bell into connection with" the line.

therefore cause such trigger tube at "only one of the substations to respond and in responding this tube will connect signaling meansto the line. "This signaling means may be 'in the form of a call bell or it may be in the form of a station identification circuit. A 5 w In accordance withariotl'ier feature 0f the invention a tuned reed trigger tube "is provided at each of the substations on a multiparty line each of which is tuned to a particular frequency characterizing such station. This trigger tube maybe underswitchhook control so that while the switchhook is in its normal position the substation call bell will be connected to the line through the action of the trigger tube and while the switchhook is in its operated position as when the substation is in use, an identification circuit will be connected to the line by the action of the trigger tube.

In accordance with another feature of the invention a simple ground connection may be made to the line in response to the transmission of a particular frequency current. Since only a particular one of a plurality of these trigger tubes will be connected to the line when a substation is in use, then if the particular frequency associated with such substation is transmitted the determined frequency. Fig. 2 shows part of a telephone lineand indicates how station identification may be accomplished by means of a gas tube 'having a movable element responsive to a .particular frequency. Fig. 3 shows part of a telephone line and indicates both howselective ringing and stationidentification may be accomplished by means of a single tube having a movable element responsive to a particular frequency.

In Fig. 1 conductors I and 2 represent the two conductors of a telephone line. :Across this line is bridged a circuit containing a condenser 3 and a coil '4 which is associatedwith the gas These electrodes are immersed in an inert gas.

Electrode 6 is in the form of a magnetic reed having one end free to vibrate. This free end is .positioned at such a distance from the stationary electrode I that under ordinary conditions any current which energizes the :coil 4 will notflow in parallelthrough the ringer 8 and the tube 5.

However, if .the tuned reed 6 is properly proportioned-foruse-atthis station the alternating current throughthe coil 4 will 'set the reed 6 into vibration, whereby the gap between the'reed 6 andthe stationary electrode 1 is shortenedand the tube breaks down. Thereupon the ringing ':-curre'nt which has-also beenapplied to the :line,

flows also from line I through the ringer 8, the tube 5 to the line 2, and. the ringer 8 responds.

A plurality of arrangements of this kind may be used on a telephone party line, each of the tubes containing reeds tuned to diiferent frequencies whereby only a single ringer on the line will respond when a particular frequency is applied to such a line.

In Fig. 2 the conductors 9 and [0 represent a telephone line. When the receiver H is taken from the hook I 2 a circuit is established from the line 9 through the condenser I3 and the coil I4. The coil I4 is associated with the tube l5. Therefore, when an arrangement of this kind is used on a party line the operator at the central oflice by applying a particular frequency to the telephone line may cause the tube 15 to respond if this is the proper substation. If the operator applies the proper frequency alternating current to the line, then through the energization of coil M the tube l5 will set its movable reed l6 into vibration and the gap between the reed l6 and the stationary electrode [1 will be shortened. Direct current voltage of the correct value in accordance with well-known a telephone line.

practice will have been applied between conductor l and ground, and will cause the tube to break down and conduct current from conductor ID to ground when the gap is shortened.

Since a plurality of arrangements of this kind may be used on a telephone line the particular substation which has its receiver off its hook may be readily identified.

'In Fig. 3 the conductors l8 and I!) represent With the receiver 20 on its hook 2| an arrangement similar to that shown in Fig. 1 is obtained, so that when ringing current of the proper frequency is applied to the line a current flows through the con-denser 22.

and coil 23 to energize the gas tube 24 whereby the movable reed 25 shortens the gap to the stationary electrode 26 and causes a current flow from the line 18 through the ringer 21, the receiver hook 2|, tube 24 to line l'9.

When the receiver 20 is removed from the hook 21 then an arrangement similar to that shown in Fig. 2 is obtained. The operator at the central office may verify this substation by applying a corresponding current to the line which, flowing through the coil 23, will energize the tube 24 and cause a direct current to flow from conductor Hi to ground through the tube 24.

What is claimed is:

1. In a telephone system, a party line having a plurality of subscriber stations connected thereto, a relay at each said station responsive to a different frequency alternating current, said relay comprising a trigger tube having as one electrode thereof a magnetic reed positioned to reduce the gap between said reed and another elec-' trode su-fliciently during vibration of said reed to cause ionization of said tube, said reed being tuned to respond to a stimulus provided by said particular frequency alternating current, and signaling means connected to said line by said relay.

2. In a telephone system, a party line having a plurality of subscriber stations connected *thereto, a relay at each said station responsive to a different frequency alternating current, said relay comprising a trigger tube having as one electrode thereof a magnetic reed positioned to reduce the gap between said reed and another electrode sufiiciently during vibration of said reed to cause ionization of said tube, said reed being tuned to respond to a stimulus provided by said particular frequency alternating current, and a call bell connected to said line by said relay.

3. In a telephone system, a party line having a plurality of subscriber stations connected thereto, a relay at each said station responsive to a difierent frequency alternating current, said relay comprising a trigger tube having as one electrode thereof a magnetic reed positioned to reduce the gap between said reed and another electrode sufliciently during vibration of said reed to cause ionization of said tube, said reed being tuned to respond to a stimulus provided by said particular frequency alterating current, and a signaling circuit connected to said line by said relay.

4. In a telephone system, a party line having a plurality of subscriber stations connected thereto, a relay at each said station responsive to a different frequency alternating current, said relay comprising a trigger tube having as one electrode thereof a magnetic reed positioned to reduce the gap between said reed and another electrode sufficiently during vibration of said reed to cause ionization of said tube, said reed being tuned to respond to a stimulus provided by said particular frequency alterating current, means for connecting said relay to said line when said substation is in use and a signaling circuit connected to said line by said relay.

5. In a telephone system, a party line having a plurality of subscriber stations connected thereto, a relay at each said station responsive to a different frequency alternating current, said relay comprising a trigger tube having as one electrode thereof a magnetic reed positioned to reduce the gap between said reed and another electrode sufficiently during vibration of said reed to cause ionization of said tube, said reed being tuned to respond to a stimulus provided by said particular frequency alterating current,

switching means at each said station for placing a call bell under control of said relay when .said station is not in use and a station identification circuit under control of said relay when said station is in use and said call bell and station identification circuit.

ROBERT H. BADGLEY. 

